1. Field of the Invention
The invention relates to a device for automatically taking liquid from a bottle and more precisely a tube plug piercing assembly for taking blood samples.
In medical biology analysis laboratories there now exist compact one piece automatic devices for counting elements representative of the peripheral blood from a whole blood sample. These automatic devices determine automatically a number of parameters such as white blood corpuscles and red blood corpuscles, the amount of hemoglobin, etc . . . For that, the blood samples must be transferred from a sample taking tube to the inside of the apparatus where they are subjected to appropriate measurements. For this, a needle is plunged into the tube and sucks up the desired amount of blood. This needle must then be carefully rinsed, inside and outside before the next measurement. Certain types of automatic devices are known which are provided with a fixed needle, connected to a suction system; the user then places the blood bottle under the needle and controls the sample taking cycle. Then after releasing and restoppering the bottle manually, he must rinse the needle.
These operations, which must be carried out with the greatest care, are fairly delicate, they require the permanent presence of the operator and are not very rapid. Furthermore, since the bottle and the tube from which the sample is taken is in a normal position, with its opening directed upwardly, the end of the needle must be able to penetrate to the bottom of the bottle so as to suck up the last few millimeters of blood. That means that the needle may dip into the blood over a great part of its height, which then requires more thorough rinsing. In addition, it is difficult to place the end of the needle at the bottom of a bottle without knocking against it with the risk of breaking the needle. For these multiple reasons, a more automatized sample taking system has been sought which improves the rates and avoids the above mentioned drawbacks.
2. Description of the Prior Art
Thus the necessity has been recognized of using needles handled automatically which take the blood from a tube. This latter comes into position on request opposite said needle, after being located in a storage support formed for example by a transversally movable carriage or a roundabout. The system is also known which consists in automatically taking the liquid from an upturned tube by means of a needle which passes through the stopper of a tube, this latter being made from a sufficiently flexible material to remain sealed after ,the needle has been withdrawn, such as described in EP-A 0061317 and FR-A 25 14504. Thus, it is only possible to cause the needle to penetrate into the blood over a small part of its height and in addition to collect the last millimeters of blood remaining in the tube.
In order that such handling be ensured rapidly under the best hygenic conditions, the stoppers of the tubes must therefore be pierced automatically and reliably by means of a device which is readily associated with the automatic counting devices for which they form an efficient auxiliary apparatus.
In known systems, such for example as in the above mentioned EP-A 0061317, the piston rod which controls the mobile piece carrying the sample taking needle itself serves as guide for this mobile piece, in association with another guide, and the force exerted is not centered on this mobile piece and is cantilevered, that is to say that the movement of the needle under the action of this offcentered force may be disturbed by the play which said piece may take on, possibly causing jamming thereof. Furthermore, the system thus described uses an appreciable number of complicated profile pieces, taking up a not inconsiderable space to the detriment of mounting the assembly and its cost price.
The invention consequently provides a stopper piercing assembly for automatically taking liquid from a bottle and more particularly blood from a tube, which answers these requirements and which avoids the drawbacks experienced by known systems.